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Accurate thermodynamic properties of the argon fluid based on ab initio potentials and their uncertainty determinations
Quan-Rui Li, Pan Xu, Kai-Yuan Yang, Jie Zhao and Bo Song

Molecular dynamics simulations and an ab initio two-body potential energy are employed to investigate the thermodynamic properties of the argon fluid under various conditions, including isochoric heat capacity, speed of sound, internal energy, and pressure. To enhance the accuracy of our calculations, we specifically incorporate the ab initio three-body potential into our simulations, examining its effect on the precision of the internal energy and pressure assessments. The simulations cover the temperatures from 40 to 2000 K and densities ranging from 0.005 to 50 mol∙L⁻¹, including an assessment of the uncertainties associated with these results. The uncertainty of the simulation data is assessed by the contributions from the simulation methodology and potential models. The results of this paper are compared with the existing experimental data and the reference data. In general, our results align closely with the reference data under most thermodynamic conditions, affirming the accuracy and reliability of our results.

Keywords: Molecular dynamics; Uncertainty; Thermodynamic properties; Ab initio potentials; Argon fluid